Wichita eagle. [volume] (Wichita, Kan.) 1886-1890, 1887-11-22
ABOUT THERMOMETERS.
THE INSTRUMENTS TO WHICH ALL
RUSH IN HOT WEATHER.

The Tubes Frequently Imperfect-Record
of a Cheap Thermometer-HowT They
Are Made-The Centigrade-Cse of the
Spirit Thermometer.
During the hot spell there is no instrument
that is studied more carefully than the ther-
mometer. Every one wants to know how hot
it is each day, and all continually consult
these little glass tubes. These vary some
times several degrees at the same instant
Said dealer in thermometers to reporter;
Thermometers are very curious instru-
ments. Sometimes we find one that is all
right at certain points and at others it will
be several degrees out of the way. These
variations are caused by Irregularities In the
tube. The tubes are very frequently imper-
feet. When the tube is too large, OF course,
the registration is several degrees lower than
it should be. Sometimes the tube Is TOO
small, and then the mercury shoots up higher
than it ought to. The tubes have TO be sea-
soned. This takes several months When
glass Is new it changes, expands, contracts
and warps almost as badly as green wood.
Very often, after buying cheap therulom-
eter the customer has brought it back and
said it registered 100 degrees in the shade,
when the temperature was only ninety. The
best thermometers are made in London.
These imported thermometers are, however,
very expensive. Some very good ones are
made in this country at New Lebanon, N. Y,
and at Rochester,
HOW THEY ARE MADE
"How are they medes" was asked.
"The tube is blown to the size wanted, the
top being left open. The bulb is then heated
to expel the air, and while heated the open
end is inserted into some mercury. AS the
tube coos the mercury runs into the vacuum.
The open end is then sealed and the tube
placed on a scale. Then it is placed in water
OF known temperature and the point to
which the mercury rises is marked. Several
tests like this are made before the instrument
is offered for sale"
"How are the Thermometers proved to be
accurateW
There is place at Harvard college for
testing them. They are carefully examined
ut different temperatures and any variation
is marked. A certificate is given with every
instrument that is examined"
(Which scale do you think is the besta"
"The centigrade is the one l think should
be generally adopted. For the use of brew
ers there is a thermometer about three feet
long, with bulb about two feet in length.
The scale Of this is short, and is only marked
for few degrees above freezing point. An
other odd instrument is Of English make, and
can be read in the dark. The tube is filed
with green composition and contains phos-
phorus. Spirit Thermometers are used for
very cold climates, as mercury congeals at 80
degs. below zero. These cannot be used to
measure extreme heat, as above a certain
temperature the liquid expands too fast; it
boils at 100 degs. For very high tempera-
lures the pyrometer takes the place Of the
Thermometer. The heat is measured by the
expansion OF metals, and will accurately
register up to 700 dogs. Febrile thornom-
eters, for the use of physicians, are very care
fully made, and a certificate is sold with them
indicating their variations from perfect &C.
curacy. New York Mall and Express